Yuuguu Settai: Kotou no Gokuraku e Youkoso

Description:

Riku Ohmi can fool every girl some of the time, he can fool some girls all of the time, and he can fool all the girls into his bed at the same time. Riku was asked to help with the girl's swim team's summer training when he finds some dirty videos of the girls, Yoshino, Nagisa, and Matsuri. Not content to stick with the videos, he uses them as a leverage to score some real action.
(Source: ANN)